Free space multiple laser diode module with fast axis collimator

ABSTRACT

Systems, devices, and methods for optical engines and laser projectors that are well-suited for use in wearable heads-up displays (WHUDs) are described. Generally, the optical engines of the present disclosure integrate a plurality of laser diodes (e.g., 3 laser diodes, 4 laser diodes) within a single, hermetically or partially hermetically sealed, encapsulated package. The optical engines include an optical director element that includes a curved reflective surface (e.g., parabolic cylinder) that redirects laser light beams and collimates the same along the fast axes thereof. Such optical engines may have various advantages over existing designs including, for example, smaller volumes, better manufacturability, faster modulation speed, etc. WHUDs that employ such optical engines and laser projectors are also described.

BACKGROUND Technical Field

The present disclosure is generally directed to systems, devices, andmethods relating to optical engines, for example, optical engines forlaser projectors used in wearable heads-up displays or otherapplications.

Description of the Related Art

A projector is an optical device that projects or shines a pattern oflight onto another object (e.g., onto a surface of another object, suchas onto a projection screen) in order to display an image or video onthat other object. A projector necessarily includes a light source, anda laser projector is a projector for which the light source comprises atleast one laser. The at least one laser is temporally modulated toprovide a pattern of laser light and usually at least one controllablemirror is used to spatially distribute the modulated pattern of laserlight over a two-dimensional area of another object. The spatialdistribution of the modulated pattern of laser light produces an imageat or on the other object. In conventional scanning laser projectors, atleast one controllable mirror may be used to control the spatialdistribution, and may include: a single digital micromirror (e.g., amicroelectromechanical system (“MEMS”) based digital micromirror) thatis controllably rotatable or deformable in two dimensions, or twodigital micromirrors that are each controllably rotatable or deformableabout a respective dimension, or a digital light processing (“DLP”) chipcomprising an array of digital micromirrors.

In a conventional laser projector comprising an RGB (red/green/blue)laser module with a red laser diode, a green laser diode, and a bluelaser diode, each respective laser diode may have a correspondingrespective focusing lens. Each of the laser diodes of a laser module aretypically housed in a separate package (e.g., a TO-38 package or “can”).The relative positions of the laser diodes, the focusing lenses, and theat least one controllable mirror are all tuned and aligned so that eachlaser beam impinges on the at least one controllable mirror withsubstantially the same spot size and with substantially the same rate ofconvergence (so that all laser beams will continue to have substantiallythe same spot size as they propagate away from the laser projectortowards, e.g., a projection screen). In a conventional laser projector,it is usually possible to come up with such a configuration for allthese elements because the overall form factor of the device is not aprimary design consideration. However, in applications for which theform factor of the laser projector is an important design element, itcan be very challenging to find a configuration for the laser diodes,the focusing lenses, and the at least one controllable mirror thatsufficiently aligns the laser beams (at least in terms of spot size,spot position, and rate of convergence) while satisfying the form factorconstraints.

A head-mounted display is an electronic device that is worn on a user'shead and, when so worn, secures at least one electronic display within aviewable field of at least one of the user's eyes, regardless of theposition or orientation of the user's head. A wearable heads-up displayis a head-mounted display that enables the user to see displayed contentbut also does not prevent the user from being able to see their externalenvironment. The “display” component of a wearable heads-up display iseither transparent or at a periphery of the user's field of view so thatit does not completely block the user from being able to see theirexternal environment. A “combiner” component of a wearable heads-updisplay is the physical structure where display light and environmentallight merge as one within the user's field of view. The combiner of awearable heads-up display is typically transparent to environmentallight but includes some optical routing mechanism to direct displaylight into the user's field of view.

Examples of wearable heads-up displays include: the Google Glass®, theOptinvent Ora®, the Epson Moverio®, and the Sony Glasstron®, just toname a few.

The optical performance of a wearable heads-up display is an importantfactor in its design. When it comes to face-worn devices, users alsocare a lot about aesthetics and comfort. This is clearly highlighted bythe immensity of the eyeglass (including sunglass) frame industry.Independent of their performance limitations, many of the aforementionedexamples of wearable heads-up displays have struggled to find tractionin consumer markets because, at least in part, they lack fashion appealor comfort. Most wearable heads-up displays presented to date employrelatively large components and, as a result, are considerably bulkier,less comfortable and less stylish than conventional eyeglass frames.

BRIEF SUMMARY

An optical engine may be summarized as including a base substrate; aplurality of laser diodes bonded to the base substrate; at least onelaser diode driver circuit, the at least one laser diode driver circuitoperatively coupled to the plurality of laser diodes to selectivelydrive current to the plurality of laser diodes; a cap including at leastone wall and at least one optical window that together define aninterior volume sized and dimensioned to receive at least the pluralityof laser diodes, the cap being bonded to the base substrate to provide ahermetic or partially hermetic seal between the interior volume of thecap and a volume exterior to the cap, and the optical window positionedand oriented to allow light emitted from the plurality of laser diodesto exit the interior volume; and an optical director element bonded tothe base substrate proximate the plurality of laser diodes within theinterior volume, the optical director element including a curvedreflective surface positioned and oriented to reflect laser light fromthe plurality of laser diodes toward the optical window of the cap, andto collimate the laser light along the respective fast axes of the laserlight from the plurality of laser diodes.

The shape of the curved reflective surface of the optical directorelement may be defined by a parabolic cylinder. The parabolic cylindermay include a focal line, and the plurality of diodes may be positionedalong an axis that is collinear with the focal line of the paraboliccylinder. The optical director element may include an edge adjacent tothe plurality of laser diodes, the edge of the optical director elementmay be aligned with the focal line of the parabolic cylinder in a planethat is orthogonal to a top surface of the base substrate. The opticaldirector element may include a mirror or a prism. The plurality of laserdiodes may include a red laser diode to provide a red laser light, agreen laser diode to provide a green laser light, a blue laser diode toprovide a blue laser light, and an infrared laser diode to provideinfrared laser light. The base substrate may be formed from at least oneof low temperature co-fired ceramic (LTCC), aluminum nitride (AlN),alumina, or Kovar®. The at least one laser diode driver circuit may bebonded to a first surface of the base substrate, and the plurality oflaser diodes and the cap may be bonded to a second surface of the basesubstrate, the second surface of the base substrate opposite the firstsurface of the base substrate.

The at least one laser diode driver circuit, the plurality of laserdiodes and the cap may be bonded to a first surface of the basesubstrate. The optical engine may further include a plurality ofelectrical connections, each electrical connection operatively coupledto the at least one laser diode driver circuit and one respective laserdiode of the plurality of laser diodes, each electrical connectionpositioned at least partially between the cap and the base substrate;and an electrically insulating cover positioned between each electricalconnection and the cap.

The plurality of laser diodes and the cap may be bonded to a firstsurface of the base substrate, and the laser diode driver circuit may beseparate from the base substrate. The optical engine may furtherinclude: a plurality of electrical contacts bonded to the first surfaceof the base substrate; a plurality of electrical connections, eachelectrical connection operatively coupled to one respective electricalcontact of the plurality of electrical contacts and one respective laserdiode of the plurality of laser diodes, each electrical connectionpositioned at least partially between the cap and the base substrate;and an electrically insulating cover positioned between each electricalconnection and the cap, wherein the at least one laser diode drivercircuit is operatively coupled to the plurality of electrical contacts.

Each of the laser diodes may include one of an edge emitter laser or avertical-cavity surface-emitting laser (VCSEL). The at least one wall ofthe cap may include at least one continuous sidewall having a lowerfirst end and an upper second end, the lower first end bonded to thebase substrate, and the optical window may be hermetically or partiallyhermetically sealed to the cap proximate the upper second end.

The optical engine may further include a plurality of chip submountsbonded to the base substrate, wherein each of the plurality of laserdiodes are bonded to a corresponding one of the plurality of chipsubmounts to bond the laser diodes to the base substrate. The opticalengine may further include a plurality of collimation lenses bonded tothe optical window, each of the plurality of collimation lenses may bepositioned and oriented to receive light from a corresponding one of theplurality of laser diodes through the optical window. The optical enginemay further include a beam combiner positioned and oriented to combinelight beams received from each of the collimation lenses into a singleaggregate beam.

A wearable heads-up display (WHUD) may be summarized as including asupport structure that in use is worn on the head of a user; a laserprojector carried by the support structure. The laser projector mayinclude an optical engine. The optical engine may include a basesubstrate; a plurality of laser diodes bonded to the base substrate; atleast one laser diode driver circuit, the at least one laser diodedriver circuit operatively coupled to the plurality of laser diodes toselectively drive current to the plurality of laser diodes; a capincluding at least one wall and at least one optical window thattogether define an interior volume sized and dimensioned to receive atleast the plurality of laser diodes, the cap being bonded to the basesubstrate to provide a hermetic or partially hermetic seal between theinterior volume of the cap and a volume exterior to the cap, and theoptical window positioned and oriented to allow light emitted from theplurality of laser diodes to exit the interior volume; and an opticaldirector element bonded to the base substrate proximate the plurality oflaser diodes within the interior volume, the optical director elementincluding a curved reflective surface positioned and oriented to reflectlaser light from the plurality of laser diodes toward the optical windowof the cap, and to collimate the laser light along the respective fastaxes of the laser light from the plurality of laser diodes. The lightprojector may also include at least one scan mirror positioned toreceive laser light from the plurality of laser diodes and controllablyorientable to redirect the laser light over a range of angles.

The WHUD may also include a processor communicatively coupled to thelaser projector to modulate the generation of light signals. The laserprojector may include a beam combiner positioned and oriented to combinelight beams emitted from the plurality of laser diodes into a singleaggregate beam. The WHUD may also include a transparent combiner carriedby the support structure and positioned within a field of view of theuser, in operation the transparent combiner may direct laser light froman output of the laser projector into the field of view of the user. Theshape of the curved reflective surface of the optical director elementmay be defined by a parabolic cylinder. The parabolic cylinder mayinclude a focal line, and the plurality of diodes may be positionedalong an axis that is collinear with the focal line of the paraboliccylinder. The optical director element may include an edge adjacent tothe plurality of laser diodes, the edge of the optical director elementmay be aligned with the focal line of the parabolic cylinder in a planethat is orthogonal to a top surface of the base substrate.

The optical engine of the laser projector may further include aplurality of chip submounts bonded to the base substrate, wherein eachof the plurality of laser diodes are bonded to a corresponding one ofthe plurality of chip submounts to bond the laser diodes to the basesubstrate. The optical director element may include a mirror or a prism.The plurality of laser diodes may include a red laser diode to provide ared laser light, a green laser diode to provide a green laser light, ablue laser diode to provide a blue laser light, and an infrared laserdiode to provide infrared laser light. The base substrate may be formedfrom at least one of low temperature co-fired ceramic (LTCC), aluminumnitride (AlN), alumina, or Kovar®.

The at least one laser diode driver circuit may be bonded to a firstsurface of the base substrate, and the plurality of laser diodes and thecap may be bonded to a second surface of the base substrate, the secondsurface of the base substrate opposite the first surface of the basesubstrate.

The at least one laser diode driver circuit, the plurality of laserdiodes and the cap may be bonded to a first surface of the basesubstrate. The optical engine of the WHUD may further include: aplurality of electrical connections, each electrical connectionoperatively coupled to the at least one laser diode driver circuit andone respective laser diode of the plurality of laser diodes, eachelectrical connection positioned at least partially between the cap andthe base substrate; and an electrically insulating cover positionedbetween each electrical connection and the cap.

The plurality of laser diodes and the cap may be bonded to a firstsurface of the base substrate, and the laser diode driver circuit may beseparate from the base substrate. The optical engine of the WHUD mayfurther include: a plurality of electrical contacts bonded to the firstsurface of the base substrate; a plurality of electrical connections,each electrical connection operatively coupled to one respectiveelectrical contact of the plurality of electrical contacts and onerespective laser diode of the plurality of laser diodes, each electricalconnection positioned at least partially between the cap and the basesubstrate; and an electrically insulating cover positioned between eachelectrical connection and the cap, wherein the at least one laser diodedriver circuit is operatively coupled to the plurality of electricalcontacts.

The optical engine of the WHUD may further include a plurality ofcollimation lenses bonded to the optical window, and each of theplurality of collimation lenses may be positioned and oriented toreceive light from a corresponding one of the plurality of laser diodesthrough the optical window. Each of the laser diodes may comprise one ofan edge emitter laser or a vertical-cavity surface-emitting laser(VCSEL). The at least one wall of the cap may comprise at least onecontinuous sidewall having a lower first end and an upper second end,the lower first end bonded to the base substrate, and the optical windowis hermetically sealed to the cap proximate the upper second end.

A laser projector may be summarized as including an optical engine andat least one scan mirror. The optical engine may include a basesubstrate; a plurality of laser diodes bonded to the base substrate; atleast one laser diode driver circuit, the at least one laser diodedriver circuit operatively coupled to the plurality of laser diodes toselectively drive current to the plurality of laser diodes; a capincluding at least one wall and at least one optical window thattogether define an interior volume sized and dimensioned to receive atleast the plurality of laser diodes, the cap being bonded to the basesubstrate to provide a hermetic or partially hermetic seal between theinterior volume of the cap and a volume exterior to the cap, and theoptical window positioned and oriented to allow light emitted from theplurality of laser diodes to exit the interior volume; and an opticaldirector element bonded to the base substrate proximate the plurality oflaser diodes within the interior volume, the optical director elementincluding a curved reflective surface positioned and oriented to reflectlaser light from the plurality of laser diodes toward the optical windowof the cap, and to collimate the laser light along the respective fastaxes of the laser light from the plurality of laser diodes. The at leastone scan mirror may be positioned to receive laser light from theplurality of laser diodes and controllably orientable to redirect thelaser light over a range of angles.

The laser projector may further include a beam combiner positioned andoriented to combine light beams emitted from the plurality of laserdiodes into a single aggregate beam. The shape of the curved reflectivesurface of the optical director element may be defined by a paraboliccylinder. The parabolic cylinder may include a focal line, and theplurality of laser diodes may be positioned along an axis that iscollinear with the focal line of the parabolic cylinder. The opticaldirector element may include an edge adjacent to the plurality of laserdiodes, and the edge of the optical director element may be aligned withthe focal line of the parabolic cylinder in a plane that is orthogonalto a top surface of the base substrate.

The optical engine of the laser projector may further include aplurality of chip submounts bonded to the base substrate, wherein eachof the plurality of laser diodes are bonded to a corresponding one ofthe plurality of chip submounts to bond the laser diodes to the basesubstrate. The optical director element may include a mirror or a prism.The plurality of laser diodes may include a red laser diode to provide ared laser light, a green laser diode to provide a green laser light, ablue laser diode to provide a blue laser light, and an infrared laserdiode to provide infrared laser light. The base substrate may be formedfrom at least one of low temperature co-fired ceramic (LTCC), aluminumnitride (AlN), alumina, or Kovar®. The at least one laser diode drivercircuit may be bonded to a first surface of the base substrate, and theplurality of laser diodes and the cap may be bonded to a second surfaceof the base substrate, the second surface of the base substrate oppositethe first surface of the base substrate.

The at least one laser diode driver circuit, the plurality of laserdiodes and the cap may be bonded to a first surface of the basesubstrate. The optical engine may further include: a plurality ofelectrical connections, each electrical connection operatively coupledto the at least one laser diode driver circuit and one respective laserdiode of the plurality of laser diodes, each electrical connectionpositioned at least partially between the cap and the base substrate;and an electrically insulating cover positioned between each electricalconnection and the cap.

The plurality of laser diodes and the cap may be bonded to a firstsurface of the base substrate, and the laser diode driver circuit may beseparate from the base substrate. The optical engine of the laserprojector may further include: a plurality of electrical contacts bondedto the first surface of the base substrate; a plurality of electricalconnections, each electrical connection operatively coupled to onerespective electrical contact of the plurality of electrical contactsand one respective laser diode of the plurality of laser diodes, eachelectrical connection positioned at least partially between the cap andthe base substrate; and an electrically insulating cover positionedbetween each electrical connection and the cap, wherein the at least onelaser diode driver circuit is operatively coupled to the plurality ofelectrical contacts.

The optical engine of the laser projector may further include aplurality of collimation lenses bonded to the optical window, and eachof the plurality of collimation lenses may be positioned and oriented toreceive light from a corresponding one of the plurality of laser diodesthrough the optical window. Each of the laser diodes may comprise one ofan edge emitter laser or a vertical-cavity surface-emitting laser(VCSEL).

The at least one wall of the cap may comprise at least one continuoussidewall having a lower first end and an upper second end, the lowerfirst end bonded to the base substrate, and the optical window ishermetically sealed to the cap proximate the upper second end.

A method of operating an optical engine that includes a plurality oflaser diodes hermetically or partially hermetically sealed in anencapsulated package may be summarized as including causing theplurality of laser diodes to generate laser light; receiving the laserlight from the laser diodes by at least one optical director element;redirecting, by the at least one optical director element, the receivedlaser light toward an optical window of the encapsulated package; andcollimating, by the at least one optical director element, laser lightfrom the plurality of laser diodes along respective fast axes of thelaser light.

The method may further include collimating, by a plurality ofcollimation lenses, the laser light from the laser diodes that exits theencapsulated package via the optical window. The method may furtherinclude combining, via a beam combiner, the plurality of laser lightreceived from each of the collimation lenses into a single aggregatebeam. Causing the plurality of laser diodes to generate laser light mayinclude causing a red laser diode to generate red laser light, causing agreen laser diode to generate green laser light, causing a blue laserdiode to generate blue laser light, and causing an infrared laser diodeto generate infrared laser light. Collimating laser light from theplurality of laser diodes may include collimating laser light from theplurality of laser diodes along respective fast axes of the laser lightvia the at least one optical director element that includes a curvedreflective surface.

A method of manufacturing an optical engine may be summarized asincluding bonding an optical director element to a base substrate, theoptical director element including a curved reflective surface and anedge, the edge aligned with a focal line of the curved reflectivesurface in a plane that is orthogonal to a top surface of the basesubstrate; bonding a plurality of laser diodes to the base substrate atrespective positions wherein, for each of the plurality of laser diodes,an output facet thereof is positioned adjacent to the edge of theoptical director element to align the output facet with the focal lineof the curved reflective surface; operatively coupling at least onelaser diode driver circuit to the plurality of laser diodes; and bondinga cap to the base substrate, the cap including at least one wall and atleast one optical window that together define an interior volume sizedand dimensioned to receive at least the plurality of laser diodes andthe optical director element, the cap providing a hermetic or partiallyhermetic seal between the interior volume of the cap and a volumeexterior to the cap, and the optical window positioned and oriented toallow light emitted from the plurality of laser diodes to exit theinterior volume via the optical director element. Bonding an opticaldirector element to a base substrate may include bonding an opticaldirector element to the base substrate, and the shape of the curvedreflective surface of the optical director element may be defined by aparabolic cylinder. Bonding a plurality of laser diodes to the basesubstrate at respective positions may include bonding each of theplurality of laser diodes to a corresponding one of a plurality of chipsubmounts, and bonding the plurality of chip submounts to the basesubstrate.

The method may further include bonding the at least one laser diodedriver circuit to the base substrate. Operatively coupling at least onelaser diode driver circuit to the plurality of laser diodes may includebonding a plurality of electrical connections to the base substrate,each electrical connection operatively coupling a respective laser diodeto the at least one laser diode driver circuit. The method may furtherinclude bonding an electrically insulating cover to the base substrateover at least a portion of the plurality of electrical connections, andbonding a cap to the base substrate may include bonding at least aportion of the cap to the base substrate indirectly by bonding the atleast a portion of the cap to the electrically insulating cover.

The method may further include: bonding a plurality of electricalcontacts to the base substrate; and bonding a plurality of electricalconnections to the base substrate, each electrical connection beingoperatively coupled to a respective laser diode of the plurality oflaser diodes and to a respective electrical contact of the plurality ofelectrical contacts, and operatively coupling at least one laser diodedriver circuit to the plurality of laser diodes may include operativelycoupling the at least one laser diode driver circuit to the plurality ofelectrical contacts. The method may further include bonding anelectrically insulating cover to the base substrate over at least aportion of the plurality of electrical connections, and bonding a cap tothe base substrate may include bonding at least a portion of the cap tothe base substrate indirectly by bonding the at least a portion of thecap to the electrically insulating cover.

The method may further include positioning a plurality of collimationlenses to the optical window, each of the plurality of collimationlenses positioned and oriented to receive light from a corresponding oneof the plurality of laser diodes through the optical window. The methodmay further include positioning and orienting a beam combiner to combinelight beams received from each of the collimation lenses into a singleaggregate beam.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. For example, the shapes of variouselements and angles are not necessarily drawn to scale, and some ofthese elements may be arbitrarily enlarged and positioned to improvedrawing legibility. Further, the particular shapes of the elements asdrawn, are not necessarily intended to convey any information regardingthe actual shape of the particular elements, and may have been solelyselected for ease of recognition in the drawings.

FIG. 1A is a left side, sectional elevational view of an optical engine,in accordance with the present systems, devices, and methods.

FIG. 1B is a front side, sectional elevational view of the opticalengine also shown in FIG. 1A, in accordance with the present systems,devices, and methods.

FIG. 2 is a flow diagram of a method of operating an optical engine, inaccordance with the present systems, devices, and methods.

FIG. 3 is a schematic diagram of a wearable heads-up display with alaser projector that includes an optical engine, and a transparentcombiner in a field of view of an eye of a user, in accordance with thepresent systems, devices, and methods.

FIG. 4 is an isometric view of a wearable heads-up display with a laserprojector that includes an optical engine, in accordance with thepresent systems, devices, and methods.

FIG. 5 is a flow diagram of a method of manufacturing an optical engine,in accordance with the present systems, devices, and methods.

FIG. 6 is a left side, sectional elevational view of a portion of anoptical engine that includes a plurality of laser diodes and an opticaldirector element that includes a curved reflective surface, inaccordance with the present systems, devices, and methods.

FIG. 7 is an isometric view of a laser diode, showing a fast axis and aslow axis of a light beam generated by the laser diode, in accordancewith the present systems, devices, and methods.

FIG. 8A is a left side elevational view of an optical director element,showing a focal line thereof, in accordance with the present systems,devices, and methods.

FIG. 8B is an isometric view of the optical director element of FIG. 8A,in accordance with the present systems, devices, and methods.

FIG. 9 is a flow diagram of a method of manufacturing an optical engine,in accordance with the present systems, devices, and methods.

FIGS. 10A and 10B are isometric views showing implementations of opticalengines having differing positions for a laser diode driver circuit inaccordance with the present systems, devices, and methods.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedimplementations. However, one skilled in the relevant art will recognizethat implementations may be practiced without one or more of thesespecific details, or with other methods, components, materials, etc. Inother instances, well-known structures associated with computer systems,server computers, and/or communications networks have not been shown ordescribed in detail to avoid unnecessarily obscuring descriptions of theimplementations.

Unless the context requires otherwise, throughout the specification andclaims that follow, the word “comprising” is synonymous with“including,” and is inclusive or open-ended (i.e., does not excludeadditional, unrecited elements or method acts).

Reference throughout this specification to “one implementation” or “animplementation” means that a particular feature, structure orcharacteristic described in connection with the implementation isincluded in at least one implementation. Thus, the appearances of thephrases “in one implementation” or “in an implementation” in variousplaces throughout this specification are not necessarily all referringto the same implementation. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more implementations.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contextclearly dictates otherwise. It should also be noted that the term “or”is generally employed in its sense including “and/or” unless the contextclearly dictates otherwise.

The headings and Abstract of the Disclosure provided herein are forconvenience only and do not interpret the scope or meaning of theimplementations.

One or more implementations of the present disclosure providelaser-based optical engines, for example, laser-based optical enginesfor laser projectors used in wearable heads-up displays or otherapplications. Generally, the optical engines discussed herein integratea plurality of laser dies or diodes (e.g., 3 laser diodes, 4 laserdiodes) within a single, hermetically or partially hermetically sealed,encapsulated package. Such optical engines may have various advantagesover existing designs including, for example, smaller volume, lowerweight, better manufacturability, lower cost, faster modulation speed,etc. The material used for the optical engines discussed herein may beany suitable materials, e.g., ceramics with advantageous thermalproperties, etc. As noted above, such features are particularlyadvantages in various applications including WHUDs.

FIG. 1A is a left side, elevational sectional view of an optical engine100, which may also be referred to as a “multi-laser diode module” or an“RGB laser module,” in accordance with the present systems, devices, andmethods. FIG. 1B is a front side, elevational sectional view of theoptical engine 100. The optical engine 100 includes a base substrate 102having a top surface 104 and a bottom surface 106 opposite the topsurface. The base substrate 102 may be formed from a material that isradio frequency (RF) compatible and is suitable for hermetic sealing.For example, the base substrate 102 may be formed from low temperatureco-fired ceramic (LTCC), aluminum nitride (AlN), alumina, Kovar®, etc.

The optical engine 100 also includes a plurality of chip submounts 108a-108 d (collectively 108) bonded (e.g., attached) to the top surface104 of the base substrate 102. The plurality of chip submounts 108 arealigned in a row across a width of the optical engine 100 between theleft and right sides thereof. Each of the plurality of chip submounts108 includes a laser diode 110, also referred to as a laser chip orlaser die, bonded thereto. In particular, an infrared chip submount 108a carries an infrared laser diode 110 a, a red chip submount 108 bcarries a red laser diode 110 b, a green chip submount 108 c carries agreen laser diode 110 c, and a blue chip submount 108 d carries a bluelaser diode 110 d. In operation, the infrared laser diode 110 a providesinfrared laser light, the red laser diode 110 b, provides red laserlight, the green laser diode 110 c provides green laser light, and theblue laser diode 110 d provides blue laser light. Each of the laserdiodes 110 may comprise one of an edge emitter laser or avertical-cavity surface-emitting laser (VCSEL), for example. Each of thefour laser diode/chip submount pairs may be referred to collectively asa “laser chip on submount,” or a laser CoS 112. Thus, the optical engine100 includes an infrared laser CoS 112 a, a red laser CoS 112 b, a greenlaser CoS 112c, and a blue laser CoS 112 d. In at least someimplementations, one or more of the laser diodes 110 may be bondeddirectly to the base substrate 102 without use of a submount 108, asshown in the example provided in FIG. 6, discussed below.

The optical engine 100 also includes a laser diode driver circuit 114bonded to the bottom surface 106 of the base substrate 102. The laserdiode driver circuit 114 is operatively coupled to the plurality oflaser diodes 110 via suitable electrical connections 116 to selectivelydrive current to the plurality of laser diodes. In at least someimplementations, the laser diode driver circuit 114 may be positionedrelative to the CoSs 112 to minimize the distance between the laserdiode driver circuit 114 and the CoSs 112. Although not shown in FIGS.1A and 1B, the laser diode driver circuit 114 may be operativelycoupleable to a controller (e.g., microcontroller, microprocessor, ASIC)which controls the operation of the laser diode driver circuit 114 toselectively modulate laser light emitted by the laser diodes 110. In atleast some implementations, the laser diode driver circuit 114 may bebonded to another portion of the base substrate 102, such as the topsurface 104 of the base substrate. In at least some implementations, thelaser diode driver circuitry 114 may be remotely located and operativelycoupled to the laser diodes 110. In order to not require the use ofimpedance matched transmission lines, the size scale may be smallcompared to a wavelength (e.g., lumped element regime), where theelectrical characteristics are described by (lumped) elements likeresistance, inductance, and capacitance.

Proximate the laser diodes 110 there is positioned an optical directorelement 118. Like the chip submounts 108, the optical director element118 is bonded to the top surface 104 of the base substrate 102. Theoptical director element 118 may be bonded proximate to or adjacent eachof the chip submounts 108. In the illustrated example, the opticaldirector element 118 has a curved reflective surface and includes aplurality of planar faces. In particular, the optical director element118 includes a curved reflective surface 118 a that extends along thewidth of the optical engine 100, a rear face 118 b, a bottom face 118 cthat is bonded to the top surface 104 of the base substrate 102, a leftface 118 d, and a right face 118 e opposite the left face. The opticaldirector element 118 may comprise a mirror or a prism, for example.

The optical engine 100 also includes a cap 120 that includes a verticalsidewall 122 having a lower first end 124 and an upper second end 126opposite the first end. A flange 128 may be disposed around a perimeterof the sidewall 122 adjacent the lower first end 124. Proximate theupper second end 126 of the sidewall 122 there is a horizontal opticalwindow 130 that forms the “top” of the cap 120. The sidewall 122 and theoptical window 130 together define an interior volume 132 sized anddimensioned to receive the plurality of chip submounts 108, theplurality of laser diodes 110, and the optical director element 118. Thelower first end 124 and the flange 128 of the cap 120 are bonded to thebase substrate 102 to provide a hermetic or partially hermetic sealbetween the interior volume 132 of the cap and a volume 134 exterior tothe cap. As shown best in FIG. 1A, the optical director element 118 ispositioned and oriented to direct (e.g., reflect) laser light receivedfrom each of the plurality of laser diodes 110 upward (as shown) towardthe optical window 130 of the cap 120, wherein the laser light exits theinterior volume 132. The laser light emitted by each of the laser diodes110 includes a fast axis 111 (FIG. 1A) and a slow axis 113 (FIG. 1B)orthogonal to the fast axis. As shown in FIG. 1A, the curved reflectivesurface 118 a of the optical director element 118 collimates the laserlight along the respective fast axes 111 of the laser light receivedfrom the plurality of laser diodes 110, such that laser light 115reflected upward toward the optical window 130 by the curved reflectivesurface is collimated along the fast axis of each of the respectivelight beams. FIG. 7, discussed below, illustrates an example laserdiode, such as one of the laser diodes 110, showing a fast axis and aslow axis of a light beam generated by the laser diode. Although theoptical director element 118 is shown as a single element thatcollimates the light from each of the laser diodes, in at least someimplementations individual collimators (fast and slow axis) may beprovided for each of the laser diodes. For example, the optical directorelement 118 may be replaced with a row of four fast axis collimators, orfour fast axis collimators may be positioned to collimate light beamsfrom the four laser diodes 110 before or after the light beams aredirected by the optical director element 118.

In at least some implementations, the shape of the curved reflectivesurface 118 a of the optical director element 118 may be defined by aparabolic cylinder (e.g., a section of a cylinder having a cross sectionthat is a parabola), such as an off-axis parabolic cylinder. For atleast some implementations, the shape of the curved reflective surface118 a may be referred to as a “single curvature” or “2D curvature”surface, for example. In at least some implementations, an output facet117 of each of the laser diodes 110 may be aligned with a focal line ofthe parabolic cylinder. For example, the output facets 117 of each ofthe laser diodes 110 may be aligned along an axis 109 (FIG. 1A) that iscollinear with the focal line of the parabolic cylinder formed by thecurved reflective surface 118 a, which causes the optical directorelement 118 to collimate light emitted by the laser diodes 110 along thefast axis of each of the beams of light. This feature reduces theexternal dimensions of the required optics and allows for bettercircularization of the beams of laser light.

The cap 120 may have a round shape, rectangular shape, or other shape.Thus, the vertical sidewall 122 may comprise a continuously curvedsidewall, a plurality (e.g., four) of adjacent planar portions, etc. Theoptical window 130 may comprise an entire top of the cap 120, or maycomprise only a portion thereof. In at least some implementations, theoptical window 130 may be located on the sidewall 122 rather thanpositioned as a top of the cap 120, and the laser diodes 110 and/or theoptical director element 118 may be positioned and oriented to directthe laser light from the laser diodes toward the optical window on thesidewall 122. In at least some implementations, the cap 120 may includea plurality of optical windows instead of a single optical window.

The optical engine 100 also includes four collimation/pointing lenses136 a-136 d (collectively 136), one for each of the four laser diodes110 a-136 d, respectively, that are bonded to a top surface 138 of theoptical window 130. Each of the plurality of collimation lenses 136 ispositioned and oriented to receive light from a corresponding one of thelaser diodes 110 through the optical window 130. In particular, thecollimation lens 136 a receives light from the infrared laser diode 110a via the optical director element 118 and the optical window 130, thecollimation lens 136 b receives light from the red laser diode 110 b,via the optical director element and the optical window, the collimationlens 136 c receives light from the green laser diode 110 c via theoptical director element and the optical window, and the collimationlens 136 d receives light from the blue laser diode 110 d via theoptical director element and the optical window.

Each of the collimation lenses 136 is operative to receive laser lightfrom a respective one of the laser diodes 110, and to generate a singlecolor beam. In particular, the collimation lens 136 a receives infraredlaser light from the infrared laser diode 110 a and produces an infraredlaser beam 138 a, the collimation lens 136 b receives red laser lightfrom the red laser diode 110 b, and produces a red laser beam 138 b, thecollimation lens 136 c receives green laser light from the green laserdiode 110 c and produces a green laser beam 138 c, and the collimationlens 136 d receives blue laser light from the blue laser diode 110 d andproduces a blue laser beam 138 d.

The optical engine 100 may also include, or may be positioned proximateto, a beam combiner 140 that is positioned and oriented to combine thelight beams 138 a-138 d received from each of the collimation lenses 136into a single aggregate beam 142. As an example, the beam combiner 140may include one or more diffractive optical elements (DOE) and/or one ormore refractive/reflective optical elements that combine the differentcolor beams 138 a-138 d in order to achieve coaxial superposition. Anexample beam combiner is shown in FIG. 3 and discussed below.

In at least some implementations, the laser CoSs 112, the opticaldirector element 118, and/or the collimation lenses 136 may bepositioned differently. As noted above, laser diode driver circuit 114may be mounted on the top surface 104 or the bottom surface 106 of thebase substrate 102, depending on the RF design and other constraints(e.g., package size). In at least some implementations, the opticalengine 100 may not include the optical director element 118, and thelaser light may be directed from the laser diodes 110 toward thecollimation lenses 136 without requiring an intermediate opticaldirector element. Additionally, in at least some implementations, one ormore of the laser diodes may be mounted directly on the base substrate102 without use of a submount.

For the sake of a controlled atmosphere inside the interior volume 132,it may be desirable to have no organic compounds inside the interiorvolume 132. In at least some implementations, the components of theoptical engine 100 may be bonded together using no adhesives. In otherimplementations, a low amount of adhesives may be used to bond at leastone of the components, which may reduce cost while providing arelatively low risk of organic contamination for a determined lifetime(e.g., 2 or more years) of the optical engine 100. The use of adhesivesmay result in a partially hermetic seal, but this partially hermeticseal may be acceptable in certain applications. In one exampleapplication, even in an environment with only partial hermiticity, thelife of laser diodes 110 and transparency of optical window 130 may bemaintained longer than the life of a battery of a device, such thatpartial hermiticity may be acceptable for the devices. In some cases,even protecting interior volume 132 from particulate with a dust covermay be sufficient to maintain laser diodes 110 and transparency ofoptical window 130 for the intended lifespan of the device. In somecases, laser diodes 110 and transparency of optical window 130 may lastfor the intended lifespan of the device even without a protective cover.Various bonding processes (e.g., attaching processes) for the opticalengine 100 are discussed below with reference to FIG. 5.

FIG. 2 is a flow diagram of a method 200 of operating an optical engine,in accordance with the present systems, devices, and methods. The method200 may be implemented using the optical engine 100 of FIGS. 1A-1B, forexample. It should be appreciated that methods of operating opticalengines according to the present disclosure may include fewer oradditional acts than set forth in the method 200. Further, the actsdiscussed below may be performed in an order different than the orderpresented herein.

At 202, at least one controller may cause a plurality of laser diodes ofan optical engine to generate laser light. As discussed above, theplurality of laser diodes may be hermetically or partially hermeticallysealed in an encapsulated package. The laser diodes may produce lightsequentially and/or simultaneously with each other. At 204, at least oneoptical director element may receive the laser light from the laserdiodes. The optical director element may comprise a mirror or a prism,for example. As discussed above, in at least some implementations theoptical engine may be designed such that laser light exits the opticalengine without use of an optical director element.

At 206, the at least one optical director element may direct thereceived laser light toward an optical window of the encapsulatedpackage. For example, the optical director element may reflect thereceived laser light toward the optical window of the encapsulatedpackage. As discussed above, the optical director element may include acurved surface that collimates the fast axis of the laser light emittedby the plurality of diodes.

At 208, a plurality of collimation lenses may collimate the laser lightfrom the laser diodes that exits the encapsulated package via theoptical window to generate a plurality of differently colored laserlight beams. The collimation lenses may be positioned inside or outsideof the encapsulated package. As an example, the collimation lenses maybe physically coupled to the optical window of the encapsulated package.

At 210, a beam combiner may combine the plurality of laser light beamsreceived from each of the collimation lenses into a single aggregatebeam. The beam combiner may include one or more diffractive opticalelements (DOE) that combine different color beams in order to achievecoaxial superposition, for example. The beam combiner may include one ormore DOEs and/or one or more refractive/reflective optical elements. Anexample beam combiner is shown in FIG. 3 and discussed below.

FIG. 3 is a schematic diagram of a wearable heads-up display (WHUD) 300with an exemplary laser projector 302, and a transparent combiner 304 ina field of view of an eye 306 of a user of the WHUD, in accordance withthe present systems, devices, and methods. The WHUD 300 includes asupport structure (not shown), with the general shape and appearance ofan eyeglasses frame, carrying an eyeglass lens 308 with the transparentcombiner 304, and the laser projector 302.

The laser projector 302 comprises a controller or processor 310, anoptical engine 312 comprising four laser diodes 314 a, 314 b, 314 c, 314d (collectively 314) communicatively coupled to the processor 310, abeam combiner 316, and a scan mirror 318. The optical engine 312 may besimilar or identical to the optical engine 100 discussed above withreference to FIGS. 1A and 1B. Generally, the term “processor” refers tohardware circuitry, and may include any of microprocessors,microcontrollers, application specific integrated circuits (ASICs),digital signal processors (DSPs), programmable gate arrays (PGAs),and/or programmable logic controllers (PLCs), or any other integrated ornon-integrated circuit.

During operation of the WHUD 300, the processor 310 modulates lightoutput from the laser diodes 314, which includes a first red laser diode314 a (R), a second green laser diode 314 b (G), a third blue laserdiode 314 c (B), and a fourth infrared laser diode 314 d (IR). The firstlaser diode 314 a emits a first (e.g., red) light signal 320, the secondlaser diode 314 b emits a second (e.g., green) light signal 322, thethird laser diode 314 c emits a third (e.g., blue) light signal 324, andthe fourth laser diode 314 d emits a fourth (e.g., infrared) lightsignal 326. All four of light signals 320, 322, 324, and 326 enter orimpinge on the beam combiner 316. Beam combiner 316 could for example bebased on any of the beam combiners described in U.S. Provisional PatentApplication Ser. No. 62/438,725, U.S. Non-Provisional patent applicationSer. No. 15/848,265 (U.S. Publication Number 2018/0180885), U.S.Non-Provisional patent application Ser. No. 15/848,388 (U.S. PublicationNumber 2018/0180886), U.S. Provisional Patent Application Ser. No.62/450,218, U.S. Non-Provisional patent application Ser. No. 15/852,188(U.S. Publication Number 2018/0210215), U.S. Non-Provisional patentapplication Ser. No. 15/852,282, (U.S. Publication Number 2018/0210213),and/or U.S. Non-Provisional patent application Ser. No. 15/852,205 (U.S.Publication Number 2018/0210216).

In the illustrated example, the beam combiner 316 includes opticalelements 328, 330, 332, and 334. The first light signal 320 is emittedtowards the first optical element 328 and reflected by the first opticalelement 328 of the beam combiner 316 towards the second optical element330 of the beam combiner 316. The second light signal 322 is alsodirected towards the second optical element 330. The second opticalelement 330 is formed of a dichroic material that is transmissive of thered wavelength of the first light signal 320 and reflective of the greenwavelength of the second light signal 322. Therefore, the second opticalelement 330 transmits the first light signal 320 and reflects the secondlight signal 322. The second optical element 330 combines the firstlight signal 320 and the second light signal 322 into a single aggregatebeam (shown as separate beams for illustrative purposes) and routes theaggregate beam towards the third optical element 332 of the beamcombiner 316.

The third light signal 324 is also routed towards the third opticalelement 332. The third optical element 332 is formed of a dichroicmaterial that is transmissive of the wavelengths of light (e.g., red andgreen) in the aggregate beam comprising the first light signal 320 andthe second light signal 322 and reflective of the blue wavelength of thethird light signal 324. Accordingly, the third optical element 332transmits the aggregate beam comprising the first light signal 320 andthe second light signal 322 and reflects the third light signal 324. Inthis way, the third optical element 332 adds the third light signal 324to the aggregate beam such that the aggregate beam comprises the lightsignals 320, 322, and 324 (shown as separate beams for illustrativepurposes) and routes the aggregate beam towards the fourth opticalelement 334 in the beam combiner 316.

The fourth light signal 326 is also routed towards the fourth opticalelement 334. The fourth optical element 334 is formed of a dichroicmaterial that is transmissive of the visible wavelengths of light (e.g.,red, green, and blue) in the aggregate beam comprising the first lightsignal 320, the second light signal 322, and the third light signal 324and reflective of the infrared wavelength of the fourth light signal326. Accordingly, the fourth optical element 334 transmits the aggregatebeam comprising the first light signal 320, the second light signal 322,and the third light signal 324 and reflects the fourth light signal 326.In this way, the fourth optical element 334 adds the fourth light signal326 to the aggregate beam such that the aggregate beam 336 comprisesportions of the light signals 320, 322, 324, and 326. The fourth opticalelement 334 routes the aggregate beam 336 towards the controllable scanmirror 318.

The scan mirror 318 is controllably orientable and scans (e.g. rasterscans) the beam 336 to the eye 306 of the user of the WHUD 300. Inparticular, the controllable scan mirror 318 scans the laser light ontothe transparent combiner 304 carried by the eyeglass lens 308. The scanmirror 318 may be a single bi-axial scan mirror or two single-axis scanmirrors may be used to scan the laser light onto the transparentcombiner 304, for example. In at least some implementations, thetransparent combiner 304 may be a holographic combiner with at least oneholographic optical element. The transparent combiner 304 redirects thelaser light towards a field of view of the eye 306 of the user. Thelaser light redirected towards the eye 306 of the user may be collimatedby the transparent combiner 304, wherein the spot at the transparentcombiner 304 is approximately the same size and shape as the spot at theeye 306 of the user. The laser light may be converged by the eye 306 toa focal point at the retina of eye 306 and creates an image that isfocused. The visible light may create display content in the field ofview of the user, and the infrared light may illuminate the eye 306 ofthe user for the purpose of eye tracking.

FIG. 4 is a schematic diagram of a wearable heads-up display (WHUD) 400with a laser projector 402 in accordance with the present systems,devices, and methods. WHUD 400 includes a support structure 404 with theshape and appearance of a pair of eyeglasses that in use is worn on thehead of the user. The support structure 404 carries multiple components,including eyeglass lens 406, a transparent combiner 408, the laserprojector 402, and a controller or processor 410. The laser projector402 may be similar or identical to the laser projector 302 of FIG. 3.For example, the laser projector 402 may include an optical engine, suchas the optical engine 100 or the optical engine 312. The laser projector402 may be communicatively coupled to the controller 410 (e.g.,microprocessor) which controls the operation of the projector 402, asdiscussed above. The controller 410 may include or may becommunicatively coupled to a non-transitory processor-readable storagemedium (e.g., memory circuits such as ROM, RAM, FLASH, EEPROM, memoryregisters, magnetic disks, optical disks, other storage), and thecontroller may execute data and/or instruction from the non-transitoryprocessor readable storage medium to control the operation of the laserprojector 402.

In operation of the WHUD 400, the controller 410 controls the laserprojector 402 to emit laser light. As discussed above with reference toFIG. 3, the laser projector 402 generates and directs an aggregate beam(e.g., aggregate beam 336 of FIG. 3) toward the transparent combiner 408via at least one controllable mirror (not shown in FIG. 4). Theaggregate beam is directed towards a field of view of an eye of a userby the transparent combiner 408. The transparent combiner 408 maycollimate the aggregate beam such that the spot of the laser lightincident on the eye of the user is at least approximately the same sizeand shape as the spot at transparent combiner 408. The transparentcombiner 408 may be a holographic combiner that includes at least oneholographic optical element.

FIG. 5 is a flow diagram of a method 500 of manufacturing an opticalengine, in accordance with the present systems, devices, and methods.The method 500 may be implemented to manufacture the optical engine 100of FIGS. 1A-1B or the optical engine 312 of FIG. 3, for example. Itshould be appreciated that methods of manufacturing optical enginesaccording to the present disclosure may include fewer or additional actsthan set forth in the method 500. Further, the acts discussed below maybe performed in an order different than the order presented herein.

At 502, a plurality of laser diodes may be bonded to a respectiveplurality of submounts. In at least some implementations, this methodmay be performed by an entity different than that manufacturing theoptical engine. For example, in at least some implementations, one ormore of the plurality of laser diodes (e.g., green laser diode, bluelaser diode) may be purchased as already assembled laser CoSs. For easeof handling and simplification of the overall process, in at least someimplementations it may be advantageous to also bond laser diodes thatcannot be procured on submounts to a submount as well. As a non-limitingexample, in at least some implementations, one or more of the laserdiodes may be bonded to a corresponding submount using an eutectic goldtin (AuSn) solder process, which is flux-free and requires heating uptop 280° C.

At 504, the plurality of CoSs may be bonded to a base substrate.Alternatively, act 502 could be skipped for at least one or all of thelaser diodes, and act 504 could comprise bonding the at least one or allof the laser diodes directly to the base substrate, such as discussedlater with regards to FIG. 9. The base substrate may be formed from amaterial that is RF compatible and is suitable for hermetic sealing. Forexample, the base substrate may be formed from low temperature co-firedceramic (LTCC), aluminum nitride (AlN), alumina, Kovar®, etc. Sinceseveral CoSs are bonded next to each other on the same base substrate,it may be advantageous to either “step-solder” them sequentially or touse a bonding technique that does not rely on re-melting of soldermaterials. For step-soldering, each subsequent soldering step utilizes aprocess temperature that is less than the process temperatures ofprevious solder steps to prevent re-melting of solder materials. It mayalso be important that the laser diode-to-submount bonding does notre-melt during bonding of the CoSs to the base substrate. Bondingtechnologies other than step-soldering that may be used include parallelsoldering of all CoS in reflow oven process, thermosonic orthermocompression bonding, transient liquid phase (TLP) bonding, lasersoldering, etc. Some of these example bonding technologies are discussedbelow.

For parallel soldering of all CoSs in a reflow oven process, appropriatetooling is required to assure proper bonding and alignment during theprocess. An advantage of this process is the parallel and hence timeefficient bonding of all CoSs at once and even many assemblies inparallel. A possible disadvantage of this process is the potential lossof the alignment of components during the reflow process. Generally, asoldering cycle ideally needs a few minutes of dwell time. Preheatingmay be used to reduce the soldering time, which requires a few minutesfor such a process depending on the thermal mass of the components beingbonded. Thus, a batch process may be used with regular soldering toreduce the assembly costs with high throughput at the expense ofalignment tolerance.

For thermosonic or thermocompression bonding, thick gold metallizationmay be used but no extra solder layer is required. The temperatures forthermocompression bonding might be as high as 300 to 350° C. to have agood bond with a good thermal conductivity. Thermosonic bonding may beused to reduce the pressure and temperature needed for bonding, whichmay be required for at least some components that might not tolerate thetemperatures required for thermocompression bonding.

Transient liquid phase (TLP) bonding may also be used. There are manydifferent reaction couples that may be used, including gold-tin,copper-tin, etc. With this method, a liquid phase is formed during thebonding which will solidify at the same temperature. The re-meltingtemperatures of the bond are much higher than the solderingtemperatures.

In at least some implementations, laser soldering may be used to bondsome or all of the components of the optical engine. Generally, thethermal characteristic of the parts to be bonded may be important whenimplementing a laser soldering process.

Subsequent reflows of solder are not recommended due to liquid phasereaction or dissolution mechanisms which may reduce the reliability ofthe joint. This could result in voiding at the interface or a reductionin strength of the joint itself. In order to mitigate potential reflowdissolution problems, other options can be taken into consideration,which do not rely on extreme heating of the device and can be favorablein terms of production cost. For example, bonding of the base substratewith adhesives (electrically conductive for common mass, ornon-conductive for floating) may be acceptable with respect to heattransfer and out-gassing as discussed regarding partial hermetic sealingabove.

Further, in at least some implementations, a reactive multi-layer foilmaterial (e.g., NanoFoil®) or a similar material may be used as a solderpre-form, which enables localized heat transfer. A reactive multi-layerfoil material is a metallic material based on a plurality (e.g.,hundreds, thousands) of reactive foils (aluminum and nickel) thatenables die-attach soldering (e.g., silicon chip onto stainless steelpart). In such implementations, dedicated heat transfer supportmetallizations may be deposited onto the two components being joinedtogether. This method may be more advantageous for CoS-to-base substratemounting compared to chip-to-submount bonding. Generally, bonding usingreactive multi-layer foil materials enables furnace-free,low-temperature soldering of transparent or non-transparent components,without reaching the bonding temperatures for solder reflow processes.Reactive multi-layer foil materials can be patterned with a ps-laserinto exact preform shapes.

At 506, the optical director element may be bonded to the base substrateproximate the laser CoSs. The optical director element may be bonded tothe base substrate using any suitable bonding process, including thebonding processes discussed above with reference to act 504.

At 508, the laser diode driver circuit may optionally be bonded to thebase substrate. As noted above, the laser diode driver circuit may bebonded to the base substrate such that the distance between the laserdiode driver circuit and the laser CoSs is minimized. This may alsocomprise positioning a plurality of electrical connections whichoperatively couple the laser diode driver circuit to the plurality oflaser diodes. In alternative implementations, the laser diode drivercircuit may be bonded to a separate base substrate from the othercomponents mentioned above. The process used to bond the laser diodedriver circuit to a base substrate may be any suitable bonding process,such as bonding processes commonly used to bond surface mount devices(SMD) to circuit boards. In other alternative implementations, the laserdiode driver circuit may be mounted directly to a frame of a WHUD. Forimplementations where the laser diode drive circuit is not bonded to thesame base substrate as the other components mentioned above, a pluralityof electrical contacts and electrical connections could be bonded to thebase substrate, each electrical connection operatively connecting arespective electrical contact to a respective laser diode. Subsequently,the at least one laser driver circuit could be operatively coupled tothe electrical contacts, which will then electrically couple the laserdiode drive circuit to the electrical connections and consequently tothe laser diodes. An exemplary arrangement of electrical connections andelectrical contacts is discussed later with reference to FIG. 10B.

At 510, the cap may be bonded to the base substrate to form a hermeticor partially hermetic seal as discussed above between the interiorvolume of the encapsulated package and an exterior environment. As notedabove, it may be desirable to maintain a specific atmosphere for thelaser diode chips for reliability reasons. In at least someimplementations, adhesive sealing may be undesirable because of the highpermeability of gases. This is especially the case for blue laserdiodes, which emit blue laser light that may bake contamination onfacets and windows, thereby reducing transparency of the optical window.However, as detailed above regarding FIGS. 1A and 1B, partialhermeticity, a particulate dust cover, or even no protective cover maybe acceptable for certain applications. In implementations where the capwould be bonded over electrical connections which connect the at leastone laser diode driver circuit to the plurality of laser diodes, such aswhen the at least one laser diode driver circuit is bonded to the sameside of a base substrate as the laser diodes, or when the at least onelaser diode driver circuit is coupled to electrical contacts bonded tothe same side of the base substrate as the laser diodes, an electricallyinsulating cover can first be bonded to the base substrate over theelectrical connections. Subsequently, the cap can be bonded at leastpartially to the electrically insulating cover, and potentially to aportion of the base substrate if the insulating cover does not fullyencircle the intended interior volume. In this way, at least a portionof the cap will be bonded to the base substrate indirectly by beingbonded to the electrically insulating cover. In some implementations,the entire cap could be bonded to the base substrate indirectly by beingbonded to an electrically insulating cover which encircles the intendedinterior volume. Exemplary electrically insulating covers are discussedlater with reference to FIGS. 10A and 10B.

During the sealing process, the atmosphere may be defined by floodingthe package accordingly. For example, the interior volume of theencapsulated package may be flooded with an oxygen enriched atmospherethat burns off contaminants which tend to form on interfaces where thelaser beam is present. The sealing itself may also be performed so as toprevent the exchange between the package atmosphere and the environment.Due to limitations concerning the allowed sealing temperature, e.g., thecomponents inside the package should not be influenced, in at least someimplementations seam welding or laser assisted soldering/diffusionbonding may be used. In at least some implementations, localized sealingusing a combination of seam welding and laser soldering may be used.

At 512, the collimation lenses may be actively aligned. For example,once the laser diode driver circuit has been bonded and the cap has beensealed, the laser diodes can be turned on and the collimations lensesfor each laser diode can be actively aligned. In at least someimplementations, each of the collimation lenses may be positioned tooptimize spot as well as pointing for each of the respective laserdiodes.

At 514, the beam combiner may be positioned to receive and combineindividual laser beams into an aggregate beam. As discussed above, thebeam combiner may include one or more diffractive optical elementsand/or one or more refractive/reflective elements that function tocombine the different color beams into an aggregate beam. The aggregatebeam may be provided to other components or modules, such as a scanmirror of a laser projector, etc.

FIG. 6 is a left side, sectional elevational view of a portion of anoptical engine 600. The optical engine 600 may include components thatmay be similar or identical to the components of the optical enginesdiscussed above. Accordingly, a discussion of all of the components ofthe optical engine 600 is not repeated herein in the interest ofbrevity.

The optical engine 600 includes a plurality of laser diodes or laserdies 602 mounted directly (i.e., without a chip submount) on a topsurface 604 of a base substrate 606. In at least some implementations,one or more of the laser diodes 602 may be mounted on the top surface604 of the base substrate 606 via a chip submount. The optical engine600 also includes an optical director element 608 that includes a curvedreflective surface 610 which collimates laser light emitted by the laserdiodes 602 along the respective fast axes 611 thereof. The opticaldirector element 608 includes an edge 612 proximate the laser diodes 602that is coplanar with a plane 614 that is orthogonal to the top surface604 of the base substrate 606. The optical director element 608 may besimilar or identical to the optical director element 118 shown in FIG.1A and 1B.

In the illustrated implementation, the curved reflective surface 610 mayinclude a focal line 616 (shown as a point in the view of FIG. 6) thatresides in the plane 614. The laser diodes 602 are positioned such thatoutput facets 618 of the laser diodes are positioned adjacent to (i.e.,abutted against) the edge 612 of the optical director element 608. Thisfeature allows the edge 612 of the optical director element 608 to beused to passively position the laser diodes 602 on the top surface 604of the base substrate 606. Generally, the optical director element 608may have a depth d selected such that the emitter portions of the laserdiodes 602 are positioned at the focal line 616 of the curved reflectivesurface 610 when the laser diodes 602 (or chip submounts when used) areabutted against the edge 612 of the optical director element 608.

FIG. 7 is an isometric view of a laser diode 700. The laser diode 700may be similar or identical to the various laser diodes discussedherein. The laser diode 700 outputs a laser light beam 702 via an outputfacet 704 of the laser diode. FIG. 7 shows the divergence of the light702 emitting from the laser diode 700. As shown, the light beam 702 maydiverge by a substantial amount along a fast axis 706 (or perpendicularaxis) and by a lesser amount in the slow axis 708 (parallel axis). As anon-limiting example, in at least some implementations, the light beam702 may diverge with full width half maximum (FWHM) angles of up to 40degrees in the fast axis direction 706 and up to 10 degrees in the slowaxis direction 708. This divergence results in a rapidly expandingelliptical cone. As discussed above, by utilizing an optical directorelement that collimates the beam 702 in the fast axis direction 706, theexternal dimensions of the optics may be reduced and bettercircularization of the beam may be achieved.

FIG. 8A is a left side elevational view of an optical director element800, and FIG. 8B is an isometric view of the optical director element.The optical director element 800 may be similar or identical to theother optical director elements described herein. The optical directorelement 800 includes a curved reflective surface 802. In at least someimplementations, the curved reflective surface has a shape of anoff-axis parabolic cylinder that has a focal line 804. As discussedabove, in an optical engine, the optical director element 800 may bepositioned relative to a row of laser diodes such that the emitterportions (e.g., output facets) of the laser diodes are aligned with orcollinear to the focal line 804 of the parabolic cylinder. Thus, beams806 emitted from the focal line 804 are collimated in the fast axisdirection by the curved reflective surface, as discussed above.

Additionally, in at least some implementations, the optical directorelement 800 may include an edge 808 that is aligned with the focal line804 of the parabolic cylinder in a plane 810 that is orthogonal to a topsurface of a base substrate to which the optical director element may bebonded. Thus, as discussed above, the edge 808 may be used to align arow of laser diodes relative to the optical director element 800 byabutting the laser diodes against the edge, which positions outputfacets of the laser diodes in alignment with the focal line 804 of theparabolic cylinder. More generally, optical director element 800 may bedesigned to have a depth such that emitter portions of laser diodes arealigned with the focal line 804 when the laser diodes (or chipsubmounts) are positioned adjacent to the edge 808 to passively alignthe laser diodes with the optical director element 800.

FIG. 9 is a flow diagram of a method 900 of manufacturing an opticalengine, in accordance with the present systems, devices, and methods.The method 900 may be implemented to manufacture the optical enginesdiscussed herein, for example. It should be appreciated that methods ofmanufacturing optical engines according to the present disclosure mayinclude fewer or additional acts than set forth in the method 900.Further, the acts discussed below may be performed in an order differentthan the order presented herein.

At 902, an optical director element may be bonded to a base substrate.The optical director element may include a curved reflective surface(e.g., parabolic surface) and an edge. The edge may be aligned with afocal line of the curved reflective surface. For example, the edge maybe aligned with the focal line of the curved reflective surface in aplane that is orthogonal to a top surface of the base substrate. Theedge may also be laterally offset from the focal line by a knowndistance. For example, in at least some implementations, the edge may besized and dimensioned such that an emitter of a laser diode is alignedwith the focal line when an edge of the laser diode, or an edge of achip submount that supports a laser diode, is positioned adjacent theedge of the optical director element.

At 904, a plurality of laser diodes may be bonded to the base substrate.Optionally, some or all of the laser diodes may be mounted ontocorresponding chip submounts which are bonded to the base substrate. Thebase substrate may be formed from a material that is RF compatible andis suitable for hermetic sealing. For example, the base substrate may beformed from low temperature co-fired ceramic (LTCC), aluminum nitride(AlN), alumina, Kovar®, etc. Since several laser diodes are bonded nextto each other on the same base substrate, it may be advantageous toeither “step-solder” them sequentially or to use a bonding techniquethat does not rely on re-melting of solder materials. Several bondingtechniques in this regard are discussed above with reference to FIG. 5.The plurality of laser diodes may be bonded at respective positionswherein, for each of the plurality of laser diodes, an output facetthereof is positioned adjacent to the edge of the optical directorelement to align the output facet with the focal line of the curvedreflective surface. As discussed above, in at least someimplementations, if the emitters of the laser diodes are not in the sameplane as an edge of the laser diodes (or chip submounts), the edge ofthe optical director element may be sized and dimensioned to align theemitters with the focal line of the reflective curved surface whenpositioned adjacent the optical director element.

At 906, a laser diode driver circuit may optionally be bonded to thebase substrate. As noted above, the laser diode driver circuit may bebonded to the base substrate such that the distance between the laserdiode driver circuit and the laser diodes is minimized. As noted above,the laser diode driver circuit may be bonded to any suitable portion ofthe base substrate, such as the top surface or the bottom surface of thebase substrate. The process used to bond the laser diode driver circuitto the base substrate may be any suitable bonding process, such asbonding processes commonly used to bond surface mount devices (SMD) tocircuit boards. In alternative implementations, the laser diode drivercircuit may be bonded to a separate base substrate from the othercomponents mentioned above. In other alternative implementations, thelaser diode driver circuit may be mounted directly to a frame of a WHUD.

At 908, the laser diode driver circuit may be operatively coupled to theplurality of laser diodes. For example, the laser diode driver circuitmay be operatively coupled to the plurality of laser diodes via suitableelectrical connections to selectively drive current to the plurality oflaser diodes. For implementations where the laser diode drive circuit isnot bonded to the same base substrate as the other components mentionedabove, a plurality of electrical contacts and electrical connectionscould be bonded to the base substrate, each electrical connectionoperatively connecting a respective electrical contact to a respectivelaser diode. Subsequently, the at least one laser driver circuit couldbe operatively coupled to the electrical contacts, which will thenelectrically couple the laser diode drive circuit to the electricalconnections and consequently to the laser diodes. An exemplaryarrangement of electrical connections and electrical contacts isdiscussed later with reference to FIG. 10B.

The laser diode driver circuit may be operatively coupleable to acontroller (e.g., microcontroller, microprocessor, ASIC) which controlsthe operation of the laser diode driver circuit to selectively modulatelaser light emitted by the laser diodes.

At 910, a cap may be bonded to the base substrate to form a hermetic orpartially hermetic seal between the interior volume of the encapsulatedpackage and an exterior environment. As noted above, it may be desirableto maintain a specific atmosphere for the laser diode chips forreliability reasons. In at least some implementations, adhesive sealingmay be undesirable because of the high permeability of gases. This isespecially the case for blue laser diodes, which emit blue laser lightthat may bake contamination on facets and windows, thereby reducingtransparency of the optical window. However, as detailed above regardingFIGS. 1A and 1B, partial hermeticity, a particulate dust cover, or evenno protective cover may be acceptable for certain applications. Inimplementations where the cap would be bonded over electricalconnections which connect the at least one laser diode driver circuit tothe plurality of laser diodes, such as if the at least one laser diodedriver circuit is bonded to the same side of a base substrate as thelaser diodes, or if the at least one laser diode driver circuit iscoupled to electrical contacts bonded to the same side of the basesubstrate as the laser diodes, an electrically insulating cover canfirst be bonded to the base substrate over the electrical connections.Subsequently, the cap can be bonded at least partially to theelectrically insulating cover, and potentially to a portion of the basesubstrate if the insulating cover does not fully encircle the intendedinterior volume. In this way, at least a portion of the cap will bebonded to the base substrate indirectly by being bonded to theelectrically insulating cover. In some implementations, the entire capcould be bonded to the base substrate indirectly by being bonded to anelectrically insulating cover which encircles the intended interiorvolume. Exemplary electrically insulating covers are discussed laterwith reference to FIGS. 10A and 10B.

During the sealing process, the atmosphere may be defined by floodingthe package accordingly. For example, the interior volume of theencapsulated package may be flooded with an oxygen enriched atmospherethat burns off contaminants which tend to form on interfaces where thelaser beam is present. The sealing itself may also be performed so as toprevent the exchange between the package atmosphere and the environment.Due to limitations concerning the allowed sealing temperature, e.g., thecomponents inside the package should not be influenced, in at least someimplementations seam welding or laser assisted soldering/diffusionbonding may be used.

In at least some implementations, a collimation lenses may be activelyaligned. For example, once the laser diode driver circuit has beenbonded and the cap has been sealed, the laser diodes can be turned onand the collimations lenses for each laser diode can be activelyaligned. In at least some implementations, each of the collimationlenses may be positioned to optimize spot as well as pointing for eachof the respective laser diodes.

In at least some implementations, a beam combiner may be positioned toreceive and combine individual laser beams into an aggregate beam. Asdiscussed above, the beam combiner may include one or more diffractiveoptical elements and/or one or more refractive/reflective elements thatfunction to combine the different color beams into an aggregate beam.The aggregate beam may be provided to other components or modules, suchas a scan mirror of a laser projector, etc.

FIGS. 10A and 10B are isometric views showing implementations of opticalengines having differing positions for a laser diode driver circuit. Theimplementations shown in FIGS. 10A and 10B are similar in at least somerespects to the implementation of FIGS. 1A and 1B, and one skilled inthe art will appreciate that the description regarding FIGS. 1A and 1Bis applicable to the implementations of FIGS. 10A and 10B unless contextclearly dictates otherwise.

FIG. 10A shows an optical engine 1000 a which includes a base substrate1002. The base substrate 1002 may be formed from a material that isradio frequency (RF) compatible and is suitable for hermetic sealing.For example, the base substrate 1002 may be formed from low temperatureco-fired ceramic (LTCC), aluminum nitride (AlN), alumina, Kovar®, etc.

The optical engine 1000 a also includes a plurality of laser diodesaligned in a row across a width of the optical engine 1000 a, includingan infrared laser diode 1010 a, a red laser diode 1010 b, a green laserdiode 1010 c, and a blue laser diode 1010 d. In operation, the infraredlaser diode 1010 a provides infrared laser light, the red laser diode1010 b, provides red laser light, the green laser diode 1010 c providesgreen laser light, and the blue laser diode 1010 d provides blue laserlight. Each of the laser diodes may comprise one of an edge emitterlaser or a vertical-cavity surface-emitting laser (VCSEL), for example.In FIG. 10A, laser diodes 1010 a, 1010 b, 1010 c, and 1010 d are shownas being bonded (e.g., attached) directly to base substrate 1002,similar to as in FIG. 6, but one skilled in the art will appreciate thatlaser diodes 1010 a, 1010 b, 1010 c, and 1010 d could each be mounted ona respective submount, similar to as in FIGS. 1A and 1B.

The optical engine 1000 a also includes a laser diode driver circuit1014 which can be bonded to the same surface of base substrate 1002 asthe laser diodes 1010 a, 1010 b, 1010 c, 1010 d. In alternativeimplementations, laser diode driver circuit 1014 can be bonded to aseparate base substrate, such as in FIG. 10B discussed later. The laserdiode driver circuit 1014 is operatively coupled to the plurality oflaser diodes 1010 a, 1010 b, 1010 c, and 1010 d via respectiveelectrical connections 1016 a, 1016 b, 1016 c, 1016 d to selectivelydrive current to the plurality of laser diodes. In at least someimplementations, the laser diode driver circuit 1014 may be positionedrelative to the laser diodes 1010 a, 1010 b, 1010 c, and 1010 d tominimize the distance between the laser diode driver circuit 1014 andthe laser diodes. Although not shown in FIG. 10A, the laser diode drivercircuit 1014 may be operatively coupleable to a controller (e.g.,microcontroller, microprocessor, ASIC) which controls the operation ofthe laser diode driver circuit 1014 to selectively modulate laser lightemitted by the laser diodes 1010 a, 1010 b, 1010 c, and 1010 d. In atleast some implementations, the laser diode driver circuit 1014 may bebonded to another portion of the base substrate 1002, such as the bottomsurface of the base substrate 1002. In at least some implementations,the laser diode driver circuitry 1014 may be remotely located andoperatively coupled to the laser diodes 1010 a, 1010 b, 1010 c, and 1010d. In order to not require the use of impedance matched transmissionlines, the size scale may be small compared to a wavelength (e.g.,lumped element regime), where the electrical characteristics aredescribed by (lumped) elements like resistance, inductance, andcapacitance.

Proximate the laser diodes 1010 a, 1010 b, 1010 c, and 1010 d there ispositioned an optical director element 1018. Like the laser diodes 1010a, 1010 b, 1010 c, and 1010 d, the optical director element 1018 isbonded to the top surface of the base substrate 1002. The opticaldirector element 1018 may be bonded proximate to or adjacent each of thelaser diodes 1010 a, 1010 b, 1010 c, and 1010 d. In the illustratedexample, the optical director element 1018 has a curved reflectivesurface and includes a plurality of planar faces, similar to opticaldirector element 118 in FIGS. 1A and 1B. The optical director element1018 may comprise a mirror or a prism, for example.

The optical engine 1000 a also includes a cap 1020 similar to cap 120 inFIGS. 1A and 1B. For clarity, cap 1020 is shown as being transparent inFIG. 10A, though this is not necessarily the case, and cap 1020 can beformed of an opaque material. Cap 1020 includes a horizontal opticalwindow 1030 that forms the “top” of the cap 1020. Although opticalwindow 1030 in FIG. 10A is shown as comprising the entire top of cap1020, in alternative implementations optical window could comprise onlya portion of the top of cap 1020. Cap 1020 including optical window 1030defines an interior volume sized and dimensioned to receive theplurality of laser diodes 1010 a, 1010 b, 1010 c, 1010 d, and theoptical director element 1018. Cap 1020 is bonded to the base substrate1002 to provide a hermetic or partially hermetic seal between theinterior volume of the cap 1020 and a volume exterior to the cap 1020.

The optical director element 1018 is positioned and oriented to direct(e.g., reflect) laser light received from each of the plurality of laserdiodes 1010 a, 1010 b, 1010 c, and 1010 d upward toward the opticalwindow 1030 of the cap 1020, wherein the laser light exits the interiorvolume, similar to FIGS. 1A and 1B. The curved reflective surface of theoptical director element 1018 collimates the laser light along fast axesof the laser light received from the plurality of laser diodes 1010 a,1010 b, 1010 c, and 1010 d, such that laser light reflected upwardtoward the optical window 1030 by the curved reflective surface iscollimated along the fast axis of each of the respective light beams,similar to as described for FIGS. 1A and 1B. FIG. 7, discussed above,illustrates an example laser diode, such as one of the laser diodes 1010a, 1010 b, 1010 c, or 1010 d, showing a fast axis and a slow axis of alight beam generated by the laser diode. Although the optical directorelement 1018 is shown as a single element that collimates the light fromeach of the laser diodes, in at least some implementations individualcollimators (fast and slow axis) may be provided for each of the laserdiodes. For example, the optical director element 1018 may be replacedwith a row of four fast axis collimators, or four fast axis collimatorsmay be positioned to collimate light beams from the four laser diodes1010 a, 1010 b, 1010 c, and 1010 d before or after the light beams aredirected by the optical director element 1018.

The cap 1020 may have a round shape, rectangular shape, or other shape,similarly to as described regarding FIGS. 1A and 1B above. The opticalwindow 1030 may comprise an entire top of the cap 1020, or may compriseonly a portion thereof. In at least some implementations, the opticalwindow 1030 may be located on a sidewall of cap 1020 rather thanpositioned as a top of the cap 1020, and the laser diodes 1010 a, 1010b, 1010 c, 1010 d and/or the optical director element 1018 may bepositioned and oriented to direct the laser light from the laser diodestoward the optical window on the sidewall. In at least someimplementations, the cap 1020 may include a plurality of optical windowsinstead of a single optical window.

The optical engine 1000 a can also include four collimation/pointinglenses similarly to as discussed regarding FIG. 1A and 1B above. Each ofthe collimation lenses can be operative to receive laser light from arespective one of the laser diodes 1010 a, 1010 b, 1010 c, or 1010 d,and to generate a single color beam.

The optical engine 1000 a may also include, or may be positionedproximate to, a beam combiner that is positioned and oriented to combinethe light beams received from each of the collimation lenses or laserdiodes 1010 a, 1010 b, 1010 c, or 1010 d into a single aggregate beam.As an example, the beam combiner may include one or more diffractiveoptical elements (DOE) and/or one or more refractive/reflective opticalelements that combine the different color beams in order to achievecoaxial superposition. An example beam combiner is shown in FIG. 3 anddiscussed above.

In at least some implementations, the laser diodes 1010 a, 1010 b, 1010c, 1010 d, the optical director element 1018, and/or the collimationlenses may be positioned differently. As noted above, laser diode drivercircuit 1014 may be mounted on a top surface or a bottom surface of thebase substrate 1002, depending on the RF design and other constraints(e.g., package size). In at least some implementations, the opticalengine 1000 a may not include the optical director element 1018, and thelaser light may be directed from the laser diodes 1010 a, 1010 b, 1010c, and 1010 d toward collimation lenses without requiring anintermediate optical director element. Additionally, in at least someimplementations, one or more of the laser diodes may be mounted directlyon the base substrate 1002 with a submount.

Optical engine 1000 a in FIG. 10A also includes an electricallyinsulating cover 1040. In FIG. 10A, laser diodes 1010 a, 1010 b, 1010 c,and 1010 d are each connected to laser diode driver circuitry 1014 by arespective electrical connection 1016 a, 1016 b, 1016 c, or 1016 d.Electrical connections 1016 a, 1016 b, 1016 c, and 1016 d run across asurface of the base substrate 1002. Electrically insulating cover 1040is placed, adhered, formed, or otherwise positioned over electricalconnections 1016 a, 1016 b, 1016 c, and 1016 d, such that each of theelectrical connections 1016 a, 1016 b, 1016 c, and 1016 d run throughelectrically insulating cover 1040. Cap 1020 is placed, adhered, formed,or otherwise positioned over electrically insulating cover 1040, suchthat cap 1020 does not contact any of the electrical connections 1016 a,1016 b, 1016 c, or 1016 d. For clarity, cap 1020 is shown as beingtransparent in FIG. 10A, though this is not necessarily the case, andcap 1020 can be formed of an opaque material. Electrically insulatingcover 1040 can be formed of a material with low electrical permittivitysuch as a ceramic, such that electrical signals which run throughelectrical connections 1016 a, 1016 b, 1016 c, and 1016 d do not runinto or through electrically insulating cover 1040. In this way,electrical signals which run through electrical connections 1016 a, 1016b, 1016 c, and 1016 d can be prevented from running into or through cap1020, which can be formed of an electrically conductive material.Although FIG. 10A shows electrically insulating cover 1040 as extendingalong only part of a side of cap 1020, one skilled in the art willappreciate that electrically insulating cover 1040 can extend along anentire side length of cap 1020.

One skilled in the art will appreciate that the positions of laser diodedriver circuitry 1014, electrical connections 1016 a, 1016 b, 1016 c,1016 d, and electrically insulating cover 1040 as shown in FIG. 10Acould also be applied in other implementations of the subject systems,devices and methods. For example, in the implementations of FIGS. 1A and1B, laser diode driver circuitry 114 could be positioned on top surface104 of base substrate 102, and electrical connections 116 could runacross top surface 104 under an electrically insulating cover, such thatelectrical connections 116 do not contact any conductive portion of cap120.

FIG. 10B is an isometric view an optical engine 1000 b, similar in atleast some respects to optical engine 1000 a of FIG. 10A. One skilled inthe art will appreciate that the description of optical engine 1000 a inFIG. 10A is applicable to optical engine 1000 b, in FIG. 10B, unlesscontext clearly dictates otherwise. The optical engine 1000 b, includesa base substrate 1003 a. Similar to base substrate 1002 in FIG. 10A,base substrate 1003 a may be formed from a material that is radiofrequency (RF) compatible and is suitable for hermetic sealing. Forexample, the base substrate 1003 a may be formed from low temperatureco-fired ceramic (LTCC), alumina, Kovar®, etc.

One difference between optical engine 1000 b, in FIG. 10B and opticalengine 1000 a in FIG. 10A relates to what components are bonded (e.g.attached) to base substrate 1003 a. In optical engine 1000 b, each of:laser diodes 1010 a, 1010 b, 1010 c, 1010 d; cap 1020; electricalconnections 1016 a, 1016 b, 1016 c, 1016 d; and electrically insulatingcover 1040 are bonded (e.g., attached) to base substrate 1003 a.However, laser diode driver circuit 1014 is not necessarily bondeddirectly to base substrate 1003 a. Instead, laser diode driver circuit1014 could be bonded to a separate base substrate 1003 b. Similar tobase substrate 1002 in FIG. 10A and base substrate 1003 a in FIG. 10B,base substrate 1003 b may be formed from a material that is radiofrequency (RF) compatible and is suitable for hermetic sealing. Forexample, the base substrate 1003 b may be formed from low temperatureco-fired ceramic (LTCC), alumina, Kovar®, etc. In an alternativeimplementation, laser diode drive circuit 1014 may not need to be bondedto a substrate at all, and could simply be mounted directly within aframe of a WHUD.

For implementations where laser diode drive circuit 1014 is not bondedto base substrate 1003 a, electrical contacts 1017 a, 1017 b, 1017 c,and 1017 d could be bonded to base substrate 1003 a, each at an end of arespective electrical connection 1016 a, 1016 b, 1016 c, or 1016 d. Inthis way, electrical contacts 1017 a, 1017 b, 1017 c, and 1017 d couldbe used to electrically couple laser diode drive circuit 1014 toelectrical connections 1016 a, 1016 b, 1016 c, and 1016 d andconsequently laser diodes 1010 a, 1010 b, 1010 c, and 1010 d.

A person of skill in the art will appreciate that the teachings of thepresent systems, methods, and devices may be modified and/or applied inadditional applications beyond the specific WHUD implementationsdescribed herein. In some implementations, one or more optical fiber(s)may be used to guide light signals along some of the paths illustratedherein.

The WHUDs described herein may include one or more sensor(s) (e.g.,microphone, camera, thermometer, compass, altimeter, and/or others) forcollecting data from the user's environment. For example, one or morecamera(s) may be used to provide feedback to the processor of the WHUDand influence where on the display(s) any given image should bedisplayed.

The WHUDs described herein may include one or more on-board powersources (e.g., one or more battery(ies)), a wireless transceiver forsending/receiving wireless communications, and/or a tethered connectorport for coupling to a computer and/or charging the one or more on-boardpower source(s).

The above description of illustrated embodiments, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments to the precise forms disclosed. Although specificembodiments of and examples are described herein for illustrativepurposes, various equivalent modifications can be made without departingfrom the spirit and scope of the disclosure, as will be recognized bythose skilled in the relevant art. The teachings provided herein of thevarious embodiments can be applied to other portable and/or wearableelectronic devices, not necessarily the exemplary wearable electronicdevices generally described above.

For instance, the foregoing detailed description has set forth variousembodiments of the devices and/or processes via the use of blockdiagrams, schematics, and examples. Insofar as such block diagrams,schematics, and examples contain one or more functions and/oroperations, it will be understood by those skilled in the art that eachfunction and/or operation within such block diagrams, flowcharts, orexamples can be implemented, individually and/or collectively, by a widerange of hardware, software, firmware, or virtually any combinationthereof. In one embodiment, the present subject matter may beimplemented via Application Specific Integrated Circuits (ASICs).However, those skilled in the art will recognize that the embodimentsdisclosed herein, in whole or in part, can be equivalently implementedin standard integrated circuits, as one or more computer programsexecuted by one or more computers (e.g., as one or more programs runningon one or more computer systems), as one or more programs executed by onone or more controllers (e.g., microcontrollers) as one or more programsexecuted by one or more processors (e.g., microprocessors, centralprocessing units, graphical processing units), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of ordinary skill in the art in light of theteachings of this disclosure.

When logic is implemented as software and stored in memory, logic orinformation can be stored on any processor-readable medium for use by orin connection with any processor-related system or method. In thecontext of this disclosure, a memory is a processor-readable medium thatis an electronic, magnetic, optical, or other physical device or meansthat contains or stores a computer and/or processor program. Logicand/or the information can be embodied in any processor-readable mediumfor use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions associated with logic and/or information.

In the context of this specification, a “non-transitoryprocessor-readable medium” can be any element that can store the programassociated with logic and/or information for use by or in connectionwith the instruction execution system, apparatus, and/or device. Theprocessor-readable medium can be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus or device. More specific examples (anon-exhaustive list) of the computer readable medium would include thefollowing: a portable computer diskette (magnetic, compact flash card,secure digital, or the like), a random access memory (RAM), a read-onlymemory (ROM), an erasable programmable read-only memory (EPROM, EEPROM,or Flash memory), a portable compact disc read-only memory (CDROM),digital tape, and other non-transitory media.

The various embodiments described above can be combined to providefurther embodiments. To the extent that they are not inconsistent withthe specific teachings and definitions herein, all of the U.S. patents,U.S. patent application publications, U.S. patent applications, foreignpatents, foreign patent applications and non-patent publicationsreferred to in this specification and/or listed in the Application DataSheet which are owned by Thalmic Labs Inc., including at least U.S.Provisional Patent Application Ser. No. 62/438,725, U.S. Non-Provisionalpatent application Ser. No. 15/848,265 (U.S. Publication Number2018/0180885), U.S. Non-Provisional patent application Ser. No.15/848,388 (U.S. Publication Number 2018/0180886), U.S. ProvisionalPatent Application Ser. No. 62/450,218, U.S. Non-Provisional patentapplication Ser. No. 15/852,188 (U.S. Publication Number 2018/0210215),U.S. Non-Provisional patent application Ser. No. 15/852,2826, (U.S.Publication Number 2018/0210213), U.S. Non-Provisional patentapplication Ser. No. 5/852,205 (U.S. Publication Number 2018/0210216),U.S. Provisional Patent Application Ser. No. 62/575,677, U.S.Provisional Patent Application Ser. No. 62/591,550, U.S. ProvisionalPatent Application Ser. No. 62/597,294, U.S. Provisional PatentApplication Ser. No. 62/608,749, U.S. Provisional Patent ApplicationSer. No. 62/609,870, U.S. Provisional Patent Application Serial Number62/591,030, U.S. Provisional Patent Application Ser. No. 62/620,600,and/or U.S. Provisional Patent Application Ser. No. 62/576,962 areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary, to employ systems, circuitsand concepts of the various patents, applications and publications toprovide yet further embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A method of manufacturing an optical engine, the method comprising:bonding an optical director element to a base substrate, the opticaldirector element comprising a curved reflective surface and an edge, theedge aligned with a focal line of the curved reflective surface in aplane that is orthogonal to a top surface of the base substrate; bondinga plurality of laser diodes to the base substrate at respectivepositions wherein, for each of the plurality of laser diodes, an outputfacet thereof is positioned adjacent to the edge of the optical directorelement to align the output facet with the focal line of the curvedreflective surface; operatively coupling at least one laser diode drivercircuit to the plurality of laser diodes; and bonding a cap to the basesubstrate, the cap comprising at least one wall and at least one opticalwindow that together define an interior volume sized and dimensioned toreceive at least the plurality of laser diodes and the optical directorelement, the cap providing a hermetic or partially hermetic seal betweenthe interior volume of the cap and a volume exterior to the cap, and theoptical window positioned and oriented to allow light emitted from theplurality of laser diodes to exit the interior volume via the opticaldirector element.
 2. The method of claim 1 wherein bonding an opticaldirector element to a base substrate comprises bonding an opticaldirector element to the base substrate, and the shape of the curvedreflective surface of the optical director element is defined by aparabolic cylinder.
 3. The method of claim 1 wherein bonding a pluralityof laser diodes to the base substrate at respective positions comprisesbonding each of the plurality of laser diodes to a corresponding one ofa plurality of chip submounts, and bonding the plurality of chipsubmounts to the base substrate.
 4. The method of claim 1, furthercomprising bonding the at least one laser diode driver circuit to thebase substrate.
 5. The method of claim 4 wherein operatively coupling atleast one laser diode driver circuit to the plurality of laser diodescomprises bonding a plurality of electrical connections to the basesubstrate, each electrical connection operatively coupling a respectivelaser diode to the at least one laser diode driver circuit.
 6. Themethod of claim 5, further comprising bonding an electrically insulatingcover to the base substrate over at least a portion of the plurality ofelectrical connections, wherein bonding a cap to the base substratecomprises bonding at least a portion of the cap to the base substrateindirectly by bonding the at least a portion of the cap to theelectrically insulating cover.
 7. The method of claim 1, furthercomprising: bonding a plurality of electrical contacts to the basesubstrate; and bonding a plurality of electrical connections to the basesubstrate, each electrical connection being operatively coupled to arespective laser diode of the plurality of laser diodes and to arespective electrical contact of the plurality of electrical contacts,wherein operatively coupling at least one laser diode driver circuit tothe plurality of laser diodes comprises operatively coupling the atleast one laser diode driver circuit to the plurality of electricalcontacts.
 8. The method of claim 7, further comprising bonding anelectrically insulating cover to the base substrate over at least aportion of the plurality of electrical connections, wherein bonding acap to the base substrate comprises bonding at least a portion of thecap to the base substrate indirectly by bonding the at least a portionof the cap to the electrically insulating cover.
 9. The method of claim1, further comprising: positioning a plurality of collimation lenses tothe optical window, each of the plurality of collimation lensespositioned and oriented to receive light from a corresponding one of theplurality of laser diodes through the optical window.
 10. The method ofclaim 9, further comprising: positioning and orienting a beam combinerto combine light beams received from each of the collimation lenses intoa single aggregate beam.